Hi, we are on Jive Hosted 8, and we need to be able to suppress the subnav (that says Overview/Content/People/Subspaces) in a particular space. (The reason we need to remove it is that we find the users of this space get very confused by it.) How can we suppress the subnav just within a space?

You could put some CSS in a widget in that place which hides the subnav. That'd be the simplest approach.

We've customised our instance so we can configure each place with properties which tell it what to display.. we can remove what we want, including the place title, menu, etc. That customisation went mostly into template.soy, and activates a bit of CSS to do what we need.

Indeed. That's why we implemented this via place properties and alterations to template.soy.. then it's all centralised & easily upgraded in the future. If we want to know what places have what settings, we just run a d/b query. We exposed the place properties in a 'Extra Settings' page, making it easy for site admins to use.

Other people's implementations depend on what customisation methods are available to them.